The present invention relates to a thermostatic cartridge for regulating hot and cold fluids to be mixed, in particular a cartridge having concentric flow rate and temperature controls, in particular of the quarter-turn type. It also relates to a mixer tap comprising such a cartridge.
Most current taps having ceramic discs do not allow the temperature of the outlet fluid, referred to as the “mixed fluid”, to be stabilized effectively when the pressure and/or the temperature of at least one of the inlet fluids, referred to as the “cold fluid” and “hot fluid”, vary. Therefore, there have been proposed, for those taps, cartridges provided with a thermostatic element which is intended to regulate the temperature of the mixed fluid.
FR-A-2821411 describes a thermostatic cartridge of this type, referred to as having concentric controls, that is to say, a cartridge which is intended to be fitted to a tap comprising two concentric handles for the respective controls of the flow rate and temperature of the mixed fluid. Regulation of the temperature is brought about by a sliding member which is fixedly joined to a thermostatic element while the adjustment of the flow rate is brought about by two discs of ceramic material which are movably joined to each other. One of those discs is connected in terms of rotation to a control member which is fixedly joined to the handle for controlling the flow rate, while the other disc, which is connected to the casing of the cartridge, is fixed in terms of rotation. Each disc delimits an upward passage for the hot fluid, an upward passage for the cold fluid and a downward passage for the mixture of the hot and cold fluids. The heat-sensitive portion of the thermostatic regulation element is arranged in the flow path of the mixture of the hot and cold fluids. In order to improve the quality and/or speed of the thermostatic regulation, that cartridge is provided with a fixed member for generating turbulence, commonly referred to as a “turbulator”, which disrupts the flow of the mixture around the heat-sensitive portion so as to increase the turbulence thereof in order to homogenize the mixture, and to homogenize the local rate of flow at the surface of that heat-sensitive portion.
However, the presence of the turbulator inhibits the capacity for discharging the mixture at the outlet of the cartridge and therefore involves a limit of the flow rate when the tap is fully open. Conversely, for low flow rates, the turbulator does not ensure that the mixture is of a homogeneous temperature, nor that it flows along the heat-sensitive portion of the thermostatic element. In other words, the dimensions of the turbulator lead to a compromise between the desired thermostatic regulation at low flow rates and the maximum flow rate permitted by the cartridge.